Rock-drill or impact engine



APPLICATION FILED FEB. 11,1920.

ROCK DRILL R IMPACT ENGINE.

Patented Aug. 3, 1920.

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' UNITED- star-Es PATENT OFFICE.

.GEORGE WILLIAM HOWELL, 0!?- IJOS ANGELES, CALIFORNIA.

noon-mum. on mrac'r ENGINE.

Substitute for application Specification of Letters Patent.

199a. Serial no. 357,91

Engines, of which the following is a specification.

This invention relates particularly to engines for rock drills; and-although there are many objects and corresponding accomplishments of-my invention and embodied in my mechanism, yet the primary ob ect may be said to be. th ttemmentof a ma mum efficiency, and with a maximum simplicity of engine mechanism.

In my mechanism there are two members moved (preferably rcciprocated) by fluid pressure; these two reciprocat ng members being a piston or hammer and a yalve. My engine operates upon the principle of expanding an initial fluid pressure charge (the charge which initially moves one of the members in one direction), to move that member back in the o osite direction, without requiring any a, 'tional charge forthe return movement. I am aware that engines of this general nature havebeen heretofore proposed; but my invention consists of certain mechanisms and certain modes of operation whereby the above stated general mode of operation is made practicable and the efficiency of the engine raised to the h ghest point. There are several features that I particularly explain hereafter I may here mention that the single initial charge of air is expanded, stepby step, to do. all of the workin the machine. No. extra charge is used for any purpose. And I attain great efficiency by thus utilizing the BXPBJISIVQ by eliminating any losses between expansions. The result is that my engine operates upon less energy than any of which I am aware.

Reference is had to the accompanying drawings, in which, for the purpose of this specification, I have illustrated a preferred form of my engine. In said drawings, Figure 1 is a longitudinal section of the engine mechanism; 2, isa section taken on line 2-2 on Fig. 1; Fi 3 is a longitudinal section showing the movableparts in positions opposite those shown in Fig. 1; and Fig. 4

1s a. section taken on line 4.4 of Fig. 3.

The numeral 10 designates a cylindrical casing havlng two bores 11 and 12 of different diameters. In this double-bored cylinder I fit a piston or hammer 9 which has a large head end 13 and asmaller rear end 14; and this piston or hammer is preferably made solidly of a singlepiece so that it becomes an effective hammer to strike a blow,

upon each reciprocation, on any suitable member 15 at the forward end of the cylinder.

Two ports, 16 and 17 lead into-the rear.

small end 11 of the cylinder, the port 16 entering the extreme rear; end against the head 18, and the port 17 entering forward of the port 16 but somewhat behind the foremost position of the rear end of the hammer. At the extreme forward end of the large cylinder bore 12 there is a port 20; and a port 21 also is placed just forward of the rearmost position of the forwardend of the hammer.

This port 21 I may term the initial exhaust port and it has apeculiar function in cansing the movement of the controlling valve, as hereinafter described.

The rear end of the cylindrical casing is enlarged, as at 10, to hold a stationary valve sleeve 30 which has a small bore 31 at its rear end and a large bore 32 at its forward end. A valve 33 reciprocates in this valve sleeve 30, having a large head end 34 and a smaller rear end 35; and a longitudinal passage 36 extends rearwardly from the head end face of the valve to a point near the rear end where it connects with the ports 37. When the valve .is in the position shown in Fig. 1 the ports 37 register with a port 38 through the valve sleeve 30, which port 38 registers permanently with the port 16. When the valve 33 is in its rearmost position the ports register as shown in Fig. 1; while, when the valve is in its. forward position, the rear end of the small part of the valve passes the port 38 and leaves this. port open for direct entry of air or other fluid pressure from the intake port 39 through the bore 31 and ports 38 and 16 to the rear end of the smaller cylinder bore 11 to press the hammer forwardly toward the position shown in Fig. 3. It is Patented Aug. 3, 1920.

Serial No, 45,621, filed August 15, 18-15 This application filed February 11,

shown in Fig. 1, and just behind the head end of the valve when the valve is in its forward position as shown in Figs. 3 and 4. Port 21 is connected by a passage 42 with a port43 throughthe valve sleeve at the rear end ofv the large forward bore 82 of thatsleeve; so that this port 43 never communicates with the space ahead of the large end-34 of the valve. Port 41 communicates with port 43' when the valve is forward and this communication is stopped when the valve is rearward. The port 43 and the port 21 both communicate with atmosphere through the passage 44 which connects with the passage 42 and leads, through the valve 45, to atmosphere at 46. The valve 45 is provided to partially i or wholl choke the exhaust to atmosphere;

but, during full operation, this valve 45 is left wide open for free exhaust.

Having now explained. the broader features of the mechanism embodying my invention, I'proceed to the statement of the operation of that mechanism and of certain preferred details of construction. Suppose that the parts are shown .in Fig. 1 and that fluid pressure is applied through the passage 39. This fluid pressure upon the rear end of the valveimmediately presses the valve 23 forwardly to the position of Fig. 3 Fluid pressure immediately enters through the ports 38 and 16 and causes the immediate forward movement of the hammer toward the position shown in Fig. During this forward movement, before it reaches its foremost position, the rear end of the hammer'uncovers the port 17 and allows the full pressure from the cylinder 11 to pass through the port 17 and to exert itself upon the forward large face of "the valve; and when this occurs thevalve moves back to its rearmost position shown inFig. 1, due to excess of pressure on its forward face over that on its rear face. The hammer continues to move forwardly by its momentum and eX pansion of the pressure fluid behind'it, striking its blow upon the member 15. The drawings show the proportionate distance which the hammer will travel and deliver an effective blow, after uncovering port 17.

When the valve moves back to its original position, shown in Fig. 1, the port 17 is immediately connected with the port 41 ahead of the front large end of the valve, so

that the pressure from the small cylinder hen the valve moves rearwardly the initial pressure is cut off. Consequently, the charge into the small cylinder bore 11 is expanded through the passage 40 and port 20 into the forward large cylinder bore 12 ahead of the large end-13 of the. hammer. The ports and )a'ssa es bein lar e 7 and direct in their V b D 23 connection, the pressures behind and ahead of the hammer equalize; and, the total pressure on the head end of the hammer being greater than that on the rear end, the hammer will be moved back to the position shown in Fig. 1 bythis difference of pressures; the fluid constantly expanding to fill thelarger bore 12 and being constantly pressed out of'the smaller bore 11 by the rearward motion of the hammer. It will be remembered that the initial pressure through port 39 is still pressing forwardly on the small rear 'end of 'thei'alve; and, simultaneously, the reduced pressure of the expanded charge of fluid is pressing rear of fluid under pressure originally introduced wardly upon the large forward face of the valve. The area of the head end of. the valvc is such that this reduced pressure acting upon its surface will still hold the valvevback against the nitial pressure at its small rear end; but also-such that a comparatively small reduction of the reduced pressure at the head end will cause the immediate forward motion of the valve under the pressure at its rear end.

Thehammer moves rearwardly underthe influence described, and when it nears {its rearmost position it uncovers the initial 'l'lttllSiZ port 21, allowing a part of the air in the large bore 12'to'pass directly to atmo phere. This action reduces the pressure in the large bore 12 and thereby reduces the I pressure upon the forward large end of the valve ;'and the valve is immediately pressed .forward by the initial air pressure against its small rear end. hen the valve moves forwardly. to the position shown in Fig. 3,

initial pressure again enters the small rear bore 11 of the cylinder, and moves the plunger forward again, in the same manner as before described. During this forward movement the port 21 is: connected with the port 43 behind the head 34 of the valve; so

that the. pressure in the large bore 12 isexhausted directly through the port 20, passage 40, port 41, valve bore 32, port 43 and passage 44. Choking of the exhaust not only diminishes theforce of the blows but p anding will pass through with specific figures through ports; and due to slows the hammer reciprocation; for the rea son that restriction of the exhaust through the port 20 causes a cushion of fluid to remain ahead of the hammer and that restriction of the preliminaryexhaust retards that reduction in pressure which causes the for ward movement of the valve. This cushion effect may be also attained by changing the position of port 17; by moving it farther to the right in Fig. 1 the valve motion to the right will take place earlier with respect to the piston stroke and the expanding fluid port 20 into cylinder 12 ahead of the piston before it reaches the end of its stroke forward.

Not only does the initial charge of air expand to move the piston or hammer back to its initial position, but also this initial charge of air operates the valve itself; and, throughout the cycle of operations, the initial charge of air is expanded step by step,

doing a certain and definite piece of work upon each expansion. I shall now illustrate taken from a "full sized opera-ting engine. The area of the rear small end of the hammer is 1.76 7] square inches; and at an initial pressure of, say, one hundred pounds per square inch the pressure exerted on the rear end of the hammer on its forward travel will be practically 176.7 pounds. (In giving these figures I ignore the fall of pressure due to passage The initial. pressure follows the piston to-the end of its travel, and, when the port 17 is uncovered, enters this port and presses against the large forwardend of the valve. This end has an area of 0.601 square inches; and the rearward fluid pressure is therefore 60.1 pounds. The area of the small rear end. of the valve 0.196 square inches and the initial pressure against that end is therefore 19.6. The excess'pressure ward end presses the valve back to the position shown in Fig.1. Immediately the connectionof the cylinder 11 to the air supply is cut off the-air charge is expanded through the port 40 into the foward end of thelarge cylinder bore 12.] At the instant of commencement of piston movement to the right p in Fig.

1, the initial charge of-air has been expanded to occupy a space represented by the cylinder 11, the valve bore 32, and the passage l0. The initial charge has a volume equal to the volumeof the cylinder 11 (the piston stroke being inches) plus the volume of the space 32 ahead of the valve, which totals 6.635 cubic inches. Upon ex to fill the volume of the port 40, which is just one cubic inch, the total volume is then 7 cubic inches and the pressure becomes about eighty-seven poundsapThe' area on the front large end of the hammer i. 2.761 square inches; and the'total pressure at eighty-seven pounds per square inch is take place to flow of the fluid.)

from the fortherefore two hundred forty pounds. Simultaneously,'at the same pressure per square inch, the total pressure against the rear small end of the hammer is .153.5 pounds; and the excess pressure is therefore 86. 5 pounds tending to move the hammer rearwardly. hen the hammerhas moved entirely to the rear, then the space occupied by the charge of air .is approximately the valve bore 32, the port 40 and the full cylinder 12, which totals 11.1 cubic inches; and the pressure becomes about 59.7 pounds per square inch. The pressure then upon the forward large face of the piston is about 165 pounds, and the pressure on the small rearqface is 105.3 pounds; and the difference or effective pressure tending to press the piston rearwardly is 59.7 pounds. It willbe noted that the pressure is now reduced to 59.7 pounds per square inch; and the pressure,consequently, upon the large end of the valve be comes 35.9 pounds, which is still greatly in excess of the pressure of 19.64 pounds at the small rear end; but the excess is not so great but that a comparatively small exhaust covers this port, a suflicient exhaust will reduce the total pressure on the front end of the valve to. less than 19.6 l pounds. The valve is small and comparatively light; and a very small excess pressure at its rear end will move it very quickly. It

is desirable to have the valve move quickly;

and on the other hand it is desirable not to require too great a reduction of pressure on the front end of the valve. as this would require a longer time period for said reduction. And, consquently, it is desirable to bring'the expanded fluid pressure down fairly low before effecting this said reduction, so that the reduction can be made quickly through a port of practical size. 011 the other hand, the head end of the" valve is made sufficiently large so that, while the reduced pressure of 35.9 pounds-is upon it, there isno liability of any premature action of the valve. This excess of area and. pressure also provides for loss of pressure through the machine by reason of restriction of flow or leakage or any other cause. And on this point may be well to state that, owing to this particular '''feature of my device,it 18 not cause the machine to be inoperative in any way. 1 I

Having described a prefcrredform of my invention, I claim:

1. In an engine meehanismythe combina tion of a suitable casing having a cylinder with relatively large and small "bores and a valve chamber with relatively large and small bores, a reciprocating piston in the cylinder with large and small ends, a reciprocating valve in the valve chamber with large and small ends, means to conduct an initial fluid pressure to the small valve bore to press against the small end of the valve and move it forwardly, means opened by the valve when so moved to admit the initial fluid pressure to the small cylinder bore to press against the small end of the piston and move it forwardly, means opened by the piston in its forward movement to admit the fluid pressurefrom the said cylinder bore to the large valve bore to press against the large end of the valve to move it rearwardly to close oil the supply of initial fluid pressure to the small cylinder bore, means opened by the valve when moved rear'wardly to admit the fluidpressure from the small cylinderbore and from the large valve bore into the large cylinder bore to press against the large end of the piston and move it rearwardly, said last mentioned means including a port leading from the large valve bore to the large cylinder bore, means opened by the piston at the rear end of its movement to directly exhaust pressure from the large cylinder bore and thereby through the communication of the last mentioned port to exhaust pressure from the large valve bore to reduce pressure on the large end of the valve so that the initial pressure at its other end will then move it forwardly, and means including an exhaust port leading from the large valve bore and adapted to be connected with the said last mentioned port when the valve moves forwardly.

2. An engine mechanism, embodying a cylinder having tandem bores of relatively large'and small diameters, a reciprocating piston with relatively large and small parts fitting said bores, there also being a valve chamber having relatively large and small tandem bores, a reciprocating valve therein having relatively largeand small ends, there being an initial pressure inlet port leading to the small valve bore, a port leading from the small valve bore at a point coverable by thesmall end of the valve to the end of the small cylinder bore,.a port leading from the small cylinder bore at a point somewhat re moved from itsend to the end of the large valve bore, a port leading from an inter-e I mediate point in the large valve bore to the end of the large cylinder bore, an exhaust port leading from the large valve bore be hind the large end of the valve to atmosphere, and an exhaust port leading from-an intermediate point in the large cylinder bore to atmosphere, the volumes and-dimensions of the parts being such that when the charge that is initially taken into the small cylinder bore then thepressure upon the large end of the valve, an initial inlet port between the small valve bore and the small cylinder bore, a port between the small cylinder bore and the large valve bore adapted to be uncovered by the small end of the piston to admit pressure from the small cylinder bore to the large valve bore to act against the large end of the valve, an exhaust port leading from'the large valve bore behind the large end of the valve to atmosphere,an ex haust port leading between the end of the 1 large cylinder bore and the large valve bore intermediate the port which admits pressure from the cylinder to the valve bore, and the exhaust port, so that reciprocation of the valve will alternately connect the last named exhaust portalternately with said two ports, and an auxiliary exhaust port to atmosphere leading from the large cylinder bore at a point to be uncovered by the large end of the piston atv or near the 'endof its stroke, the valve having a longitudinal passage leading from its large end through the valve to a pointnear the small end of the valve adapted to register with the initial pressure port when the valve is moved against the initial pressure. f V

4, An engine mechanism, embodying a cylinder haing'tandem bores of relatively large and small diameters, a reciprocating piston with relatively large and small ends fitting said bores, there also being a valve chamber having tandem bores of relatively large and small diameters, a reciprocating valve having relatively large and small parts fitting said bores, there being an initial inlet port to the end of the small valve bore to constantly apply pressure tothe small end of the valve, a port leading from the small valve bore at a point coverable bythe small end of the valve to the end of the small cylinder bore, a port leading from the small cylinder bore at a point'somewhat removed from its end to the end of the large valve bore, an exhaust port leading from the back 7 end of. the large valve bore behind the large end of the valve, an exhaust port leading from the large cylinder here at a point somewhat removed from its end and to beuncovered by the large end of the'piston, and a port leading from the end of the large largecylinder bore to the large valve bore at a point midway between the two other said ports leading to said large valve bore, the

arrangement 01 said ports being such that the reciprocation of the valve causes the last stated port to alternately communicate with the two other ports, and said valve having a longitudinal port therethrough leading from its large end to a point near its small end there communicating with transverse ports registrable with the port which leads from the small valve bore to the small cylinder bore. 10 In witness that I claim the foregoing I have hereunto subscribed my name this 3d day of Februar 1920.

GEORGlil WILLIAM HOWELL. Witness:

VIRGINIA I. BERINGER. 

